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Ok, so what we are looking at here are two slices of the mammalian retina, and they are
almost identical except for one major difference. So take a look at that for a second and see
if you can pick out that difference. (PAUSE HERE IS NEEDED) So that difference is basically
told to you by the position of the arrows, and so if we look a little closer here, actually
we don't really need to see a high resolution because really what you are doing is counting
nuclei. If you can see just below this line that I am drawing, you can see what are called
ganglion cells. Those are the innermost cells of the retina.On this side over here you can
see that there is a much larger number within the box that I drew. Whereas on this side
over here, there is a much smaller number. And point of that is that this is letting
us look at the structure of the eye and immediately know something about its function. This illustrates
a concept called convergence that you see in many sensory systems. What the Number of
ganglion cells are telling us is the amount of convergence within certain regions of the
retina. In this region on the left hand side you can see that there are more ganglion cells
and that means that there's less convergence, which means that this area on the left side
here is a portion of your retina that has much higher degree of resolution. On the right
hand side you can see that this is an area probably towards the peripheral area of your
vision where you actually don't have very good resolution. You can see differences in
the structure of the retina and really know something about its function. That's very
good to be able to see side-by-side, otherwise these two slide are very very similar.
Now we are going to take little bit closer look. So take a look at those ganglion cells
and try to guess which area of the eye you are actually in. Again you can see the really
big difference between both of these slides is the number of ganglion cells. So take a
good look at those layers. The eye is really beautiful because of its organization. Its
one of the most organized tissues you will ever see. You have there layers here. You
have the nuclei of the rods and cones right here. The bipolar cells right here. The ganglion
cells right here. So hopefully that gave you a nice comparison of the eye side-by-side
of a pretty simple tissue, which is the eye, but it's pretty cool in its level of organization.
It's really beautiful tissue.